A178180 Numbers k such that prime(2k) mod prime(k) = prime(2k+2) mod prime(k+1).

1, 8, 18, 21, 39, 40, 51, 55, 67, 85, 86, 87, 123, 175, 179, 185, 199, 200, 216, 227, 247, 248, 260, 292, 314, 351, 360, 361, 407, 413, 434, 441, 445, 465, 479, 494, 514, 515, 565, 573, 576, 580, 583, 622, 629, 670, 679, 684, 691, 698, 712, 717, 724, 734

Offset

1,2

Links

Table of n, a(n) for n=1..54.

Formula

prime(2*a(n)) mod prime(a(n)) = prime(2*a(n)+2) mod prime(a(n)+1).

Example

a(2)=8 because prime(2*8) mod prime(8) = prime(2*8+2) mod prime(8+1) = 15.

Maple

A178180:=n->`if`((ithprime(2*n) mod ithprime(n)) = (ithprime(2*n+2) mod ithprime(n+1)), n, NULL): seq(A178180(n), n=1..10^3); # Wesley Ivan Hurt, Sep 14 2014

Mathematica

Select[Range[800], Mod[Prime[2#], Prime[#]]==Mod[Prime[2#+2], Prime[#+1]]&] (* Harvey P. Dale, May 28 2019 *)

Prog

(PARI) s=[]; for(n=1, 1000, if(prime(2*n)%prime(n) == prime(2*n+2)%prime(n+1), s=concat(s, n))); s \\ Colin Barker, Jun 27 2014

Crossrefs

Cf. A000040.

Sequence in context: A277557 A108060 A279688 * A269311 A242185 A273527

Adjacent sequences: A178177 A178178 A178179 * A178181 A178182 A178183

Keyword

nonn

Author

Juri-Stepan Gerasimov, Dec 22 2010

Extensions

Corrected by R. J. Mathar, Dec 22 2010

More terms from Colin Barker, Jun 27 2014

Status

approved